User's Manual

LE910 Hardware User Guide

1vv0301089 Rev.7 – 25-10-2015

10 USB Port

The LE910 module includes a Universal Serial Bus (USB) transceiver 2.0, which operates at

USB high-speed (480Mbits/sec) and is compatible with older USB full-speed (12Mbits/sec).

10.1 USB 2.0 HS Description

The following table is listing the available signals:

PAD

Signal

I/O

Function

Type

NOTE

B15

USB_D+

I/O

USB differential Data (+)

3.3V

C15

USB_D-

I/O

USB differential Data (-)

3.3V

A13

VUSB

Power sense to activate internal

USB transceiver.

USB active: 2.0 V to

5.25 V @ max 5mA

with internal pull-down

10K

The USB_DPLUS and USB_DMINUS signals have a clock rate of 480 MHz.

The signal traces should be routed carefully. Trace lengths, number of vias and capacitive

loading should be minimized, additional ESD protection must be carefully evaluated.

The characteristic impedance value should be as close as possible to 90 Ohms differential.

NOTE:

- USB_VBUS input power is internally used to detect the USB port and start enumeration

process. It isn’t used for supplying internal LE910 USB HW block. Therefore, only

maximum of 5mA is required.

- The USB_VBUS is internally pulled-down by 10k ohm resistor. Customer host application

must take into account voltage divider with the internal pull down resistor meeting the

minimum of 2.2V input, in case that a serial resistor is placed on USB_VBUS signal.

NOTE:

In the case of not using USB communication, it is still highly recommended to place an optional

USB connector in the application board.

USB physical communication is needed in the case of SW update